Are Lumineers reversible? They had little preparation done due to bulkiness.

Pain is probably an occlusal issue.  Yes, you can have them removed but there can be additional treatment required.

I agree that the dentist should first check the bite on your lower teeth.  When you add porcelain to the front and biting edge of the lower teeth, you can increase the bite force of these teeth against the upper teeth.  Adjust the bite first.  If the pain continues, you might want to have another experience dentist examine your teeth before deciding to remove the Lumineers.  And the Lumineers must be extremely carefully removed to avoid damaging your natural teeth.  Finally, if your teeth were contoured prior to the Lumineers being placed, you probably won't be able to have them removed.  In that case find a few opinions of experienced cosmetic dentists.

Hi:The pain could be due to bad bite on the lumineers.  Please have your dentist recheck the bite.  Depending on how little preparation was done, lumineers can be taken off without any adverse effect to the tooth or sensitivity.Best,Dr. Maddahi