Hi,
there is no need to remove the PBS as storage from PVE just for a certificate change. In case of self-signed certificates, just update the fingerprint after the change on PVE side.
On a side note: PBS 2.0 and PVE 7.0 are end of life, you should upgrade to the latest available versions as soon as possible, since you do not get any security updates and bugfixes with the currently running versions.