joint account property sale?

There is no such possibility unless a competent court delivers such judgment on a case filed by one party on another.  The court verdict is the ultimate solution.

You cannot sell.

You may negotiate with your Partner or coowner to sell the property to him/her only. If the property can be divided, you may seek partition of the property to the extent of your share and then sell, if such partition results in an economic holding which can be easily sold to anybody else.

How is that there joint holding of property?