Depending on the player's playing habits, there are two ways to solve this problem.
1)Sandpaper the nut to lower the height of the strings at the 1st-12th fret; before that, you need to learn how to change the guitar nut:
Step1:Remove all the guitar strings so you can access the guitar nut. Loosen the tension of each string with the tuning keys and unwind each string from its tuning post. Pull out each string and put them aside. You can use this opportunity to install new strings for your guitar.
Step2:Use a craft knife to beat around the nut 2-3 times, It helps the nut to release from the glue,then gently take out the nut.Don’t try to make it come loose by swinging the hammer harder or you might damage your guitar.Be careful not to cut yourself when using the craft knife.
Step3:Fix the sanded nut in place with glue, carefully insert it into the slot and press it firmly into place, and let it dry for 24 hours. It is not recommended to use permanent glue (such as super glue) to fix the guitar nut, because it is difficult to remove and may damage your guitar if you want to replace it again.
2)Adjust the bridge screws to lower the strings from the 12th to 22nd fret.