Error 'picklist must contain at least one value' when you delete a picklist value

To resolve this error, you must first remove the picklist value from the Record Type's selected values before attempting to delete it from the field definition. The error occurs because the value is the only selected value for one or more record types on the object.

 

1. The Record Type which references the picklist value is stated below the error message. Take note of the Record Type under "Record Type Name".
2. Go to the said Record Type and and click "Edit" beside the picklist where the value belongs to under "Picklists Available for Editing".
3. Check if the picklist value you want to delete is under "Selected Values".
4. Highlight the picklist value and move it to the left side under "Available Values".
5. Since at least one value must be selected, make sure that there is at least one value under "Selected Values". If there is none, move a separate value over from the left side.
6. Click Save.

After you carry out the above steps, you will be able to delete the picklist value in the field definition.