Can I remove my back boiler?

I recently had a new boiler installed in my kitchen which makes my backboiler (baxi bermuda)redundant, the boiler was left in situ so I can use the fire. Now I know the fire worked with the boiler attached but it does not seem correct somehow, the guys (who were corgi registered)assured me that boiler was turned off and would not fire up(apparently has a three way gas cock and was turned to fire only position!?) Should I remove the boiler or is it ok as it is?