Is your Android phone slow and unresponsive? Is it running out of storage space and memory? Are your getting error message or problems with apps crashing? Clean and optimize the storage.

The cause, at least partly, could be due to junk files cluttering up the system. They build up over time, so here is how to find them and delete them.

A clean up of your phone's storage could solve some of the problems you are having with a lack of space, memory and crashing apps. Removing an app from your phone should be easy and you just go to Settings > Apps, tap the app you don’t want and then tap the Uninstall button. Unfortunately, this does not remove every file and folder created by the app and there are left-overs. Orphaned files that don't belong to anything and are never used.

If you like to try lots of apps in the Google Play Store you will end up with lots of junk files afterwards. If files remain after removing an app, they will remain forever because Android will never clean them up. Over time they will build up and they could consume a significant amount of space, which means less room for your photos, music and other apps.

If you install an app and it does not work, one of the things people try is uninstalling the app and then reinstalling it from the store. The problem is that if there are files left over from the original installation, they could trigger the same problem as before when the app is reinstalled. The app might just crash again. It is best to remove all the files and then perform a clean install.

Let’s take a look at an example. You should first read You have been uninstalling apps all wrong, which shows how to uninstall apps correctly and clean up the junk files that are remaining. In that article I showed how to delete an app properly and clear out the junk files afterwards. Now I will show that there are even more left-over files that have been missed.

I will be using a Samsung Galaxy phone for this, but it will work on any phone or tablet with a fairly recent version of Android.

Device Care phone storage

Pull down from the top of the screen and tap the gear icon or go to the apps drawer screen and tap Settings. Select Device Care, which is a handy utility that Samsung provides. Your phone may have a similar app, but there are also clean-up apps in the Google Play Store that do a similar thing.

It displays the amount of storage space used and free. Tap the Optimise now button to clean up a lot of junk. It is a good idea to use it once a month or when your phone's storage is nearly full. Let's take a look at the storage, tap it.

The used storage is conveniently organised into categories so that you can see the space used by apps, images, documents and so on. At the bottom is Advanced. Tap it to see an alternative view.

On this screen is an even more detailed view of the items in the phone's storage and you can easily see what is using up all the space. Actually, this phone is pretty clean because it is fairly new, but after a year or two, the storage could be nearly full. Tap Files at the bottom.

Browse files in phone storage

You can also get to this screen through the My Files app and tapping Internal Storage. If your phone does not have a way of browsing the files in the internal storage, search the Google Play Store for 'file manager' or 'file explorer'.

A list of folders is displayed and you may see some from apps you removed a long time ago. I uninstalled Lets Meditate, but as you can see there is still a Lets Meditate folder. It looks like it contains just one item, but tapping it reveals that the item is a sub-folder, which contains files.

These folders are using up storage space. OK, it isn’t a lot in this case, but that is because I try to keep a pretty clean phone and you may find much bigger folders and files than these if you have never browsed your phone's storage. The Downloads folder may contain many items you no longer need, like podcasts, audio files and so on.

It isn’t just about the storage space though, and if you reinstall an app, perhaps to try and solve a problem with it crashing or not working properly, it will reuse the old files. Delete all traces of the app and you can perform a clean install that may solve a problem you had.

Long press any file or folder to select it, such as a folder or file from an app you deleted a long time ago. A toolbar appears at the bottom to delete the item.

Take care not to delete anything you are not sure about. The folder, sub-folder and files in the screenshots are clearly associated with an app I used to have, but are no longer present. They are safe to delete. Other items may not be, so think carefully before deleting anything. If you are not sure, just leave them alone.

Related: Uninstall updates to fix problems on the Samsung Galaxy

File managers, either bundled with the phone as with Samsung devices or as apps downloaded from the Google Play Store, are great tools for expert users, but if you don't know what you are doing, you can cause problems. Take care.