If you meant Premium Services, see this support FAQ - https://ttlc.intuit.com/turbotax-support/en-us/help-article/change-service-level/remove-premium-serv...
If you meant the Premium online editions, see this to downgrade - https://ttlc.intuit.com/turbotax-support/en-us/help-article/change-service-level/downgrade-lower-pri...
