Let's say we have a status Resolved that we would like to remove from Incident ticket type. To do this, we need to:
a) go to the Resolved status detail screen (Administration tab -> Service Desk -> Requests / Incidents / Problems -> Status -> Resolved
b) click on the Request Status -> Request Transitions tab on the bottom screen
c) if there are any active transitions there, we need to inactivate them
d) this can be done by clicking on the Edit in List button, highlighting each record below and setting each record to Inactive status
e) click Save to save the changes
f) refresh the Resolved status detail form by right click and select refresh from the SDM right click menu
h) ensure that the Request Transitions tab now shows 0 active transitions
i) click on the Edit button on the Resolved status page
j) uncheck the checkbox under Requests
k) click Save
Now we should not get the error anymore.
Repeat the same process if you need to remove the Resolved status for Incidents / Problems as well.