Medicare Part A (inpatient care) is mandatory for every one who turns 65. You don't have a choice. Goods news, Part A is free.
If you don't want or need any of the other Medicare benefits, you'e not required to enroll in them.
However, if you are drawing SS when you turn 65, the feds will automatically sign you up for Part A (free) and deduct your Part B (outpatient care)from your SS check. It's about $120 a month.
Or you can decline the Part B (I did) and save the $120 or so a month they take from your SS check.
bookmark - I did not know that about Part B