I've never seen a Milich adaptor but the Leitz and Voitlander adaptors have little semi-circle cutouts around the edge. The older Leitz M-bayonet rear lenscaps (with gray plastic inserts inside) have lugs on the backside and can be used as a wrench to remove an adaptor that was left behind when the lens unscrewed. Be sure to press in the lens release of course.
I would be very very cautious about using Loctite to hold an adaptor onto a lens. There are at least 2 types of Loctite and one of them requires heating to 500F to break it loose 😱 The other type is more like crazy glue, which can be dissolved with acetone, although in my experience acetone doesn't ususally penetrate fine threads well enough to do the job. The most I would feel comfortable doing is using one or 2 TINY drops of clear nailpolish. You have to spin the lens down very quickly though because it dries really fast and you wouldn't want the lens to seem like it was all the way home if it wasn't quite, because focus would be off everywhere. I've never used any kind of threadlocker and don't plan to. Even lacking one of those old lenscaps, I find that if I hold the lock button in with one finger and place the palm of my other hand flat against the adaptor and twist, it usually comes loose.