Make it easier to find how to delete values

https://docs.opendatakit.org/collect-filling-forms/#removing-answers describes how to delete values. It uses the terminology "removing answers" which users are unlikely to search for. It would be better to use words like "clear", "delete", "values" so this section is easier to find.

Open the linked Collect documentation page and locate the “removing answers” section. Update its wording so users can find it with terms such as “clear,” “delete,” and “values,” then verify that the section still accurately describes deleting values.

Written by the indexing model from the issue text.