Didn't Pass Final Course for Undergraduate Degree - Already Have Full Time Job
You're going to have to find a way to retake that class, or an acceptable substitute, if you want to get your degree.  So that's the starting point.

I would suggest you begin by speaking to your academic advisor.  They will know about possible options for retaking the class, or other classes you might be able to take as a substitute.  You can also ask about the possibility of taking an equivalent class through another university (which might include online options) and transferring the credit - but be sure to get the specific course approved by your university in advance.

Ultimately, you might have to consider rearranging your work schedule, or even looking for a different job with more flexible hours, in order to retake the class.  Which is more important to you in the long term, this specific job, or having a college degree?

(Another thing to keep in mind - if you were offered your current job on condition of having a degree, you would likely be obligated to inform your employer that you haven't yet graduated.  If that's the case, then going on with your current job and forgetting about the failed course may not be an option anyway.)