Do I have to submit SAT II scores?

In a bout of overconfidence last fall, I signed up for three subject tests (Math 2, Physics, and Lit). It was a pretty big mistake because studying for all 3 has become overwhelming and I haven't been able to fully review for Physics or Lit.

Should I take them anyways and is it too late to go back on it? To be frank, I don't want to take either of those tests a second time in the fall, so if I should take them as planned, what should I do? Are subject tests and the regular SAT sent to colleges all together or can I choose not to include my subject test scores? If I do well on Math II can I decide to only send that one?

Yes, you can choose which subject test scores to send. SAT Score Choice allows you to choose which scores you send to which schools; however, there are some schools that require you to submit all test scores, so you should carefully review the policies of the colleges you plan on applying to.