If you have high repaying capacity, then it is advisable that you opt for less number of years for repaying the loan as it will reduce the overall burden of the interest. Though you are ready for repaying the loan as quickly as possible, but if you miss to mention this in the loan agreement, it would be tough to alter once the application is processed by the organization that is lending you the money.
In certain cases where you have repaid some installments of a previous student loan independently, you would be given the authority of branching away the Co-borrower. This is known as Co-Borrower Release and by doing so, you ensure that the loan repayment is entirely yours. This also puts you in a position where you are not hit by the Credit History of your Co-Borrower. Both of you are separate entities speaking from the loan perspective and you would hence need to take charge of repaying your loan off.
Start your research today and trust me, you will find one or the other lender who will be able to give you a loan without your co-borrower. Please note that having or not having a co-borrower for your loan is subject to the credit history of your co-borrower. If he has a good credit history, you would not mind getting him on-board for signing the loan agreement. Think twice if it is otherwise.
It is an unsaid rule in the world of loans that one needs a co-signer to ensure that the student loan gets approved. That said, it does not mean that you would not get loans if you do not have a co-signer to sign on your agreement. There are some lenders in the market who would offer loans to you with you having to worry about the co-signer.