Every speaker has sometimes felt that they want to get out of giving a presentation. So if you feel that way, it is completely normal. But let me tell you: there is no getting out of giving a presentation.
Even if you do come up with a successful excuse of getting out of a speaking gig or obligation, you still end up giving a presentation. The host will tell the audience that you were not able to make it for whatever reason and that is exactly what people will find memorable about you: that you did not appear and that you are not reliable. That is a presentation, and not a good one.
What i want you to do is to refocus your mind on what you are trying to accomplish in your career and how you can deliver this speech in the least stressful way. The way to do that is to simplify the process. I want you to start with a simple sheet of paper and start with a sentence. Think about what you want your audience to do after hearing you speak. Then you must come up with upto 5 ideas which would increase the odds of having the audience do what you want. I want you to stand up and talk about your points and record on your phone. Watch it and focus on what you do not like and point out what you did not enjoy. Take one mistake a time and practice once more reinforcing a change.
So instead of spending the whole day trying to come up with an excuse to get out of the speech, use half an hour to actually come up with an effective and non stressful speech.