I see, thanks for clarifying. As far as I know, there is no easy way to do that, at least at the moment. The best workaround I can think of is using Regex + Find and Replace.
For example, if you wanted to remove all cloze deletions from c6 to c25, you could use:
Find: \{\{c([6-9]|1[0-9]|2[0-5])::(.*?)(::(.*?))?\}\}
Replace with: $1
This is of course not the most ergonomic solution, and will not work correctly if there are nested cloze deletions (e.g, {{c6::This is {{c7::an}} example}}).