How can we make an unsaturated …

A saturated solution is that which is dissolved as much solute as it is capable of dissolving. By heating the solution a saturated solution can be changed into an unsaturated solution. Without adding any solvent it can be changed into an unsaturated solution. Example: on heating a saturated solution of sugar in high temperature, it starts dissolving.

A solution is a homogeneous mixture of two or more substances.
Component of the solution : A solution has two components. The component of a solution that is present in larger quantity is called the solvent and the component present in smaller quantity is called as solute.
Solvent +Solute = Solution
Example: Tincture Iodine. In tincture of iodine, the iodine is the solute and alcohol is the solvent. 
Types of Solutions based on Concentration:
Saturated solution: A solution which will not dissolve anymore solute is called a saturated solution.
Unsaturated solution : A solution in which more of the solute will dissolve is called an unsaturated solution.
Thus in order to convert a saturated solution into an un-saturated solution is by dilution process.
On dilution the concentration of solution decreases thus it requires more salt to be added to it to make it as saturated solution.