I set up a “button” on my ipad screen I don’t know how to get rid of.

Before I realized that I could achieve a screenshot with gestures, I followed directions to place a “button” on my desktop that was programmed to take a screenshot with a double tap. It’s translucent, square with a series of circles inside, and I can move it anywhere on the screen. Somehow, between then and now, its response to a double tap now pulls up the control center and a single pulls up the app picker.

Problem is, I don’t need it now and I have no idea what it’s called or where I can find it in the settings to deactivate it. Can anyone help?