Could run it through a regular expression \[.+?\] and empty replacement to strip out everything in [square braces].
The \[ and \] means a literal brace, not an expression.
The . means any character.
The + means one or more "any character"s.
The ? means limit the “one or more” to get the minimal number of characters to fit the expression, so it doesn’t match plain text between rich text.
This demo is handy to fiddle with the regex to get it right for what you want: