Is it permissible to withdraw from purchasing an orchard by preemption after taking possession of it and paying its price, due to discovering that the defect is greater than what was thought, and is it permissible to reclaim the money?

If the buyer became aware of the defects in the land before the sale and accepted them, and the seller did not conceal any of its defects, then the purchase is binding on him, and he does not have the right to return it or demand a reduction due to the defect. It is recommended for the seller to cancel the sale (by mutual agreement), based on the saying of the Prophet, peace and blessings be upon him: "Whoever cancels a sale for a Muslim, Allah will cancel his stumble."