Currently 'remove comments' appear to be either all or none:
You can either remove all comments, including your own and others, or all comments are locked.

There should be a permission setting so that in a space users are able to REMOVE or EDIT their own comments, but not comments of others.

One complication of this partial permission mode is nesting of comments by multiple users. However, it's not that complicated: Comments can be considered to have automatically 'quoted' when they are replied to (although the content is not duplicated), so the parent's content can no longer be edited or removed until the child is removed.

In this way, in some spaces, comments should be final and only editable by an administrator, in some, they should be mutable by yourself, and in others, they should be mutable by others (either admins, moderators, or even everyone).