The only way to be sure you have truly 'removed' it all is to "Hard Reset" the phone. The drawback to that is that it removes anything else you have installed or put on the device as well. So, should you choose to do that, be sure you back up photos, videos, etc., to a cloud account (and make sure they are actually there) before you do the "Hard Reset". I would normally say to a computer as well (for backing up) but in this case, you don't want to transfer anything to the computer that could also infect it.
If you don't want to do that full "Hard Reset" just yet, try starting the phone in "Safe Mode" and seeing if you have the same problems. If not, then it is something you should be able to remove off the phone while still in "Safe...