If strStdID is "Joe Bloggs" then what SQL are you executing?
DELETE FROM DAdmin WHERE Username = Joe Bloggs
Is that valid SQL? What if your username was "me or 1=1" then your SQL would be
DELETE FROM DAdmin WHERE Username = me or 1 = 1
what would happen then? (Google "little bobby tables" for a clue).
You need to put text parameters in quotes, however the best way of doing this is to use parameters and let ado.net sort it out for you
cmd.CommandText = "DELETE FROM DAdmin WHERE Username = @userID";
cmd.Parameters.AddWithValue ("@userID", strStdID);
cmd.ExecuteNonQuery()
If you still get the error it could be because Username is a reserved word so you might need to use square brackets to let the database know you mean the column name and not the reserved word
cmd.CommandText = "DELETE FROM DAdmin WHERE [Username] = @userID";