You do not leave very clear if the advertising that bothers you is in applications or you get everywhere on your device.

If it is the second probably have some app with addware.

If you want to remove advertising from within apps, you can, but it is neither easy, nor fast.

First you would need to root your device, which is a way to get access to many features that are locked for security or convenience.

Also install Busy Box to add certain commands to the Android system.

Then you would need an app called Lucky Patcher which allows you to modify apps to your liking, and one of its functions is to remove Google Ads.