Welcome into the forums!
Your base’s extensions can be found by opening the Extensions tab located near the top right of your base.
Furthermore, if you open the Extensions tab into fullscreen, you’ll be able to easily see all of your Extensions.
Don’t worry, the data seen here is all test data.
If you have Extensions active in your base (that you’re actively using), then they won’t be hard deleted, merely disabled.
You can proactively manage what is active/inactive by using the dialog attached to each Extension.