It appears that the real property
is already in your name (title rests in your name, the lien from the primary lender is in your name, and you are currently the one paying property taxes). From this perspective, there is nothing stopping you from selling the home.
The only question left is the enforcement of your agreement or contract with your brother. As an initial matter, I will assume that his property interests are not recorded, therefore any sale of the property would not be encumbered by this property interest, it would solely be a contract dispute between you and your brother.
If it is recorded, this makes the matter more complex. (You really will need to see an attorney to review the document and give you a legal opinion).
The interpretation regarding the contract I have provided above. If the loan terms provide that every payment must be made, then every payment must be made. If there have been substantial periods with missed payments, the brother is in breach and the other brother can take efforts to enforce the contract, including sale of the home. As this would be a non-secured loan, this is not a foreclosure and you do not need a trustee to do so.
I will caution you, please keep in mind, I cannot give you specific legal advice or instruction, and when dealing with substantial amounts of money or real property, I would advise at least consulting with local counsel to develop a plan after a review of your documents (particularly a non-traditional agreement regarding payment of a loan on real property).
While my rough interpretation is that you can simply sell the property and keep the proceeds, I would suggest checking with a local attorney (particularly if your brother has experience with the civil litigation system and is probably not afraid to complicate matters with a lawsuit). I understand that customers do not come to this forum to be told to go see a lawyer, but in some cases, that truly is the optimal expert information I can provide to protect you from pitfalls.