I use ci) and ci] quite a lot to change what happens in between the parens or brackets.
Is there a way to remove everything including the parens or brackets?
You can use the a variant: ca), ca].
The i is "inner", whereas the a is for "a" as in "a word", "a sentence", or "a [] block". I usually think of these as "inner" and "outer" ("auter?") though.
See :help text-objects for a full list and documentation, or :help objects for a brief overview.
ci) is "change inside brackets" and ca) is "change around brackets"