Marial averaged 1.3 points and 1.3 rebounds while playing under six minutes per game this season.
Tagovailoa transferred from Alabama in May.
The quarterback had announced his intent to leave the program in early February.
Hamilton averaged 9.5 points and 4.3 rebounds as a sophomore with the Eagles.
The Terps' frontcourt depth will be tested without the twin forwards.
Boone announced Thursday on Twitter that he would be leaving the program.
Jones, from Olney, transferred from Ohio State. Smith, from Baltimore, is a graduate transfer out of Clemson.
Ramsey appeared in five games in his freshman year.