Currently, there is no way to delete assessment types from the admin tool outside of a chargeable request unfortunately as this needs to be done in the tables by the SQL team to make sure that nothing further breaks from the removal.
It may be possible to delete charge unit types and contribution types so long as they haven't been used against person in the system, however you will want to test this in a non-live environment before attempting to do so in Live. You will likely see the Delete button be active and not greyed out but testing first is important.
Should you require the deletion to be carried out as work by us via the Projects SQL Team then please raise a new case online and reference the title of this article and the support team will be able to instigate that across.
Please also provide the following:
Screenshot of the Contributions window in the Admin Tool with an expanding out the relevant Assessment Type, Contribution Type, and Charge Unit Type combination clearly highlighting your request.