How do I resolve the hanging problems of an Android phone?

Things that you can do to remove the lags are:

1. Do a factory reset.
2. You can do it either from the phone settings menu, or you can go to recovery to clear the data.
3. Install a launcher like Nova Launcher. (It’s very snappy)
4. Try to disable bloatware. (Bloatware are the apps which are pre-installed by the OEM.)
5. Now the below steps need root. (You can use google to find out the way to get your phone rooted.)
6. Use Greenify as Vinayak stated. (I’ll suggest you to go-to for the pro version).
7. Goto, it’s settings and enables all the options.
8. Add all the apps in the hibernation list and then hibernate all of them.
9. Create a hibernation shortcut from greenify and press it when you start to feel the lag.
10. Only install the apps you need.
11. After you obtain root, you can delete the installed bloatware and get some additional free space.
12. Xposed Framework makes the greenify even more powerful.
13. If you’re below Android 5(Lollipop) then it’s a one-click installation.
14. But above Android 5, the process becomes a bit difficult and needs a custom recovery.
15. So, if you are comfortable with flashing and other stuff, then you must use Xposed in Android 5 and above.
16. Do tell me if I was of any help.