Suggestions: best way to deactivate/delete, and replace?

This is the most insane update of a plugin I've ever had in my 15+ years as website developer! My word...

Nobody asked for this; we used to have a nice, little lightweight plugin for only one simple feature, and now we're stuck with a full bloated membership plugin! Sad, sad, sad...

What is the best way of deactivating/deleting the 3+ version of this plugin? Did it create tables and other crap that needs to be removed, and does the default delete plugin feature a good job at this?

And any suggestions for replacing it with another plugin?