If you've already been to MEPS and signed everything, I don't think your recruiter can just discharge you.
He maybe able to start processing you for discharge but someone else has to approve it.
Have you missed a lot of DEP meetings or something? Have you got into legal trouble or made false statements that your recruiter found out about?
If you don't think that you have done anything go up the chain of command. Speak with the next person in charge of your recruiter. Even a recruiter has someone to answer to.
You may have to go to the Commanding Officer of the recruiting command where you enlisted. You do have a right to request to speak with him/her.
You need to go up the chain of command first and find out if you can stay. If you don't want to go, then you can appeal it.
If you have an entry level discharge, you may be able to enlist again but it depends on why they separated you. You have a right to know why.
I don't know if the police dept you are interested in looks at people who were denied enlistment. I guess again it would depend on why you are being denied entry....
I guarantee that it is not the sole responsibility of the recruiter to make the final decision. So you need to start going up the chain now.