FortiAuthenticator (6.1.0) cannot delete expired or revoked certificate

Hello,

I have configured FAC as CA and generatin certificates on it then exporting them into machines. Everything is working fine but when certificate has expired or revoked, I cannot delete it from list Certificate Management -> End Entities -> Users.

After I select certificate, the Delete option is gray.

I want to delete this because I have Certificate Expiry notification which should send me email with warning that certificate will expire in X days, and it's sending me mails everyday about this certificates that have already expired and I cannot delete them from expired list... I am enclosing screenshot (as you can see I cannot delete cert from list).

I would appreciate any help,

Best Regards,

Michal