Demarco Park is located behind the Home Depot in Aberdeen, just off Exit 85 (from I 95).
Home Depot Address: 979 Beards Hill Rd, Aberdeen MD 21001
Drive around either end of the shopping center and look for the gravel road through the woods.
Another option is to use the park address:
Demarco Park: 400 Ruby Drive, Aberdeen MD
This puts you in a neighborhood where you'd park on a street and walk down a hill to the pitch.