Hi mate,not sure how to remove bumper but I have repaired many dented bumpers, without removing bumper.If you can gain accesses to rear of bumper you can gently heat up the front of the bumper and surrounding area of dent and push dent out from behind.Once you have moulded back into shape cool area with water and it will remain in shape.If it looks distorted in places work on that area using same technique.Bumper will get hot so beware not to damage paintwork.You may also want to use a glove to push the dent out as it gets very hot.