If it is a Hayward Drain cover then that cover should infact have
screws. It would be nice to know who built the pool or if it is a
viynl liner, concrete, or fiberglass to better acess your sitution.
Some companies are know to glue but not many. And it would also be
nice to know why you need to remove it so maybe we can fix your problem
without removing it at all.
let me know