Add Row Deletion to FPRM

So I know you mentioned creating a ->sql for each database system but you also mentioned starting with the simplest SQL command and, for all of them, that's

DELETE FROM table_name

[WHERE condition]

So that's what this PR consists of. Let me know if you'd prefer I add the case in, just for future additions, or if there's SQL you'd prefer I'd make sure this handles (that I don't yet have here).