Salesforce Fact #714 | Error while deactivating picklist value
Have you encountered this error while deactivating a picklist value 'The picklist value you attempted to delete is the last value for the following record types'. In order to avoid the error, we need to go to the particular record type and the picklist field, then move the value from the 'Selected Values' section to 'Available Values' section and ensure there is at least one other value is selected. Now, we are good to deactivate the picklist value. Reference: https://help.salesforce.com/s/articleView?id=000386677&type=1