How can I remove Artefill from nasolabial folds? The area feels hard like cement.

Artefill removal can be performed on the nasolabial folds and lips. Cosmetically sensitive areas with facial granulomas have increased risk of soft tissue deformity after Artefill removal. Best, Dr. Karamanoukian

Before trying any surgical procedures to remove Artefill from your nasolabial folds,  I would recommend trying Kenalog or 5FU injections to see if that helps.  In some instances the injections can help and would keep you from having to have surgery.  

Bellafill works by asking your body to create scar in response to the small (a little bigger than a red blood cell) beads of PMMA that are in each syringe of Bellafill.  While this works wonderfully 99% of the time, aberrant scar can, on occasion, form and become a problem as in your case.  I have used Bellafill for over 10 years now and I also review most of the problem cases for the maker of Bellafill, Suneva Medical.  I have yet to see a case in which the product has to be removed surgically although some surgeons will just remove it without trying the non-surgical options first.
Monthly injections of small amounts of Kenalog 10 will slowly soften this heavy scar that is causing your problem.  It sometimes takes 4 or 5 injections but, in my experience, this always works.  5FU is an alternative to Kenalog 10 but again it is a serial treatment over time.  For 5FU to be effective, it needs to be done about every 7 to 10 days.

I hope that helps.

Best regards.