it seems you have partially uninstalled OX. But something remained. To find out why, please take a look at he appcenter logfiles in
If uninstalling the App completely, do the following steps on the command line:
To remove all OX related packages, first uninstall the package
univention-ox and then any remaining package with
open-xchange in the name:
Then remove all repositories that have to do with OX:
ucr unset $(ucr --keys-only search 'repository/online/component/(backend|frontend|ox)')
That should remove all of OX (except for the LDAP schema, let’s ignore that).