Booleans are bad because they don't work. They are very temperamental, eg causing your geometry to disappear. They also inevitably result in bad topology, and you need to be very careful when cleaning up after them. They usually create more work than they're worth.

Every professional modeler that I have met, myself included, stay away from them like the plague.

Regarding your comment on detaching. Why would you want to do that? You want to get rid of the polygons, so just delete them.

I HIGHLY suggest you invest in some tutorials in order to learn some of these basic skills. Take a look at our free tutorials to get started: https://simplymaya.com/autodesk-maya-...d=23&sub_cat=0