Legal Question in Constitutional Law in Oklahoma

Your question is rather vague, but in general the answer is yes. The right to defend yourself is not an obligation.

Of course, if you deliberately put yourself in harm's way your actions may qualify as a suicide attempt, which is punishable as a crime in many jurisdictions. (I don't know whether Oklahoma is one of them.) The crime consists of your attempt to cause your own death, not of your refusal to defend yourself from the harm you put in motion.

Also, depending upon the circumstances, failing to protect yourself can indicate a serious mental illness. In extreme cases this can justify involuntary confinement for a psychiatric evaluation and even long-term treatment. Such confinement is not a penalty and does not mean that the person being confined did anything illegal. Still, it is something most people would want to avoid.