To remove the scratch in acrylic you need to first use Silicon Carbide water proof paper of 600CW grade. Turn over the paper and rub the scratched area of acrylic in a circular motion. You will see the scratch disappears after few minutes. Thereafter use the Silicon Carbide water proof paper of 1200CW grade which is more fine. Again rub over the scratched area in circular motion. Then wipe off the area and you can see after some time of rubbing the scratch is completely disappeared. But it leaves the surface little dull. So you need to use some rubbing compound which is available in corporate and apply on that dull surface by a clean rag piece using circular motion. The acrylic now appears shaded at some places. Now one need to apply some muscle polish on the acrylic sheet with new and clean rag piece in circular motion. After some time you can see the acrylic looks glossy again as before the scratch.