I got charged with three charges and then did a plea deal for the lesser one. the other charges say Nolle Prosequi

Yes, if a charge was nolle prossed you can ask that it be expunged and this is routinely done. However, the other charge, if a conviction, will stay. If a probation before judgment, you have to wait a while and then can file to have that expunged too.

Maybe. It depends on the charge and your prior record. The District Court has expungement forms. Easy to fill out $30.00

If the verdict on the plea deal was probation before judgment, then you should be able to pursue expungement. However, guilty findings may not be expunged. Additional information about expungement is available at mdcourts.gov.