Hi Apulia,

You cannot remove the whole repository out of the box. If you want it to be completely removed you need to email apps[at]odoo.com and they have to approve it. You can however (since recently) unpublish all apps from a repository which is almost identical to deleting it. You can do this by going to https://apps.odoo.com/apps/dashboard/repos, clicking on the gear icon of a branch and then clicking on the "Unpublish all apps from this repo" button:

This will make the apps invisible on the appstore but allows all the user that have bought (or downloaded) your module in the past to be able to access it.

Regards,

Yenthe