sell my share in undivided joint property without consent of co owner

A.Dear Client,
Selling an undivided property might be declared void by a court of law. So the best option is to sell the property after partition. if your brother is not willing to partition the property then you can file a partition suit before the concerned court.
Thank you

A.Dear Sir,
First get issue a legal notice offering to sell to your brother if do not show interest then you can sell to any body as
per following principle.

Right To Joint Possession And Right of Pre-emption
The right of 'pre-emption' is given to the owner of immovable property to acquire another immovable property that has been sold to some other person. It is the purchase by one person before all others. ... The objective behind this right is to maintain privacy and prevent strangers to come in neighbour or in a family.
There are two views in this matter. The purchaser has no right to joint possession of the property compelling partition. He can sue all other coparceners for that purpose. [32]
If the vendee has obtained possession, the other coparceners can get him ejected by a suit. All that the purchaser is entitled to in such a suit is a declaration that he is entitled to the share of the coparcener against whom the decree has been passed.
The Bombay High Court has a different approach. It gives some discretion to the court in the matter of ejectment of a stranger purchaser. In Bhau Laxman v. Budha Manku [33] the court laid down three rules:
First, if a purchaser stranger of the undivided interest of a coparcener in a joint family property is out of possession, he should not be given joint possession with the other coparceners but should be left to his remedy of a suit for partition.
Secondly, on the other hand if the purchaser has obtained possession of the property, a coparcener who has been excluded may obtain joint possession with the purchaser.
Thirdly, the purchaser in possession need not be ejected in a suit for recovery of possession brought by an excluded coparcener. The matter should be decided on merits because he is not a trespasser. In a suitable case he may be declared to be entitled to hold (pending partition) as a tenant-in-common with other coparceners.
The issue came to be discussed by Supreme Court in M.V.S. Manikayala Rao v. M. Narasimhaswami [34] . The court held that it is well settled that a purchaser in such a case cannot claim to be put in joint possession with the other coparceners. He has only the right to ask for general partition of the joint property.