In your bit where you are updating pm_process, you first of all set the description field and then you set the Raise User guid
UPDATE pm_process
SET pm_raise_user_guid
The error PM_PROCESS table there is a foreign key constraint from a column called PM_CREATION_USER_GUID indicates that you have the Create User field populated with somebody you are trying to delete I think, and you've not set that field, only the raise user field