The issue was first brought up by @bastiencyr in #1065:

Only for dev, I just noticed that there are a lot of keys added in my repo manager which start by "vorta-test-repo...". I don't know if it is a bug but it would be nice for dev to provide a way to remove this tests repo. I have something like 650 entries 'vorta-test-repo...' in my default password manager (gnome-keyring) :(

To solve this issue, the keyring module of vorta needs a method to remove a key from the keyring. Currently I don't know of other uses of such a feature.