System Users or leftovers from AD/Exchange Takeover?

I’ve found some users in my system which are not listed as system users here:

SM_5c977e3075d840999 MSExchApproval
SM_6fa4a7d4e74d4fcfb MsExchDiscovery
SM_8cdc4c19f298483fb FederatedEmail.
SM_15dc6b554e5e4197b MsExchDiscoveryMailbox

The righthand names are followed by a string of letters and numbers.

Can I delete those users safely?
Or at least hide them as they are listed in nextcloud also which bloats the list.

Thank you very much!