My name is Ando and I have right now to write a formal letter to a very important person. But before I handle it to her I would like you to take a look at what I have done and check if there is no mistake.
The letter is as the following:
I am writing to ask you to be unregistered at Varsity College.
For some personal problems, mainly financial, I have to stop my sudies at Varsity College and go back as soon as possible in Madagascar, where I come from.
(I don't know what to write next)
While the meaning of your opening sentence can be understood, "unregistered" really isn't a word. Perhaps you can say:
I am writing to request that my registration at Varsity College be withdrawn.
where I come from
As a rule, you shouldn't end a sentence with a preposition. Maybe change it to read, "Madagascar, my homeland."
For a closing paragraph, it's always a good idea to end with something like:
I appreciate your assistance in this matter. If you have any questions, please do not hesitate to contact me.
Of course, you include your contact information (phone number, cellular phone number, email address, etc) in your letter.