It is very easy to change your existing pool into a concrete gunite pool.
Convert vinyl liner pool to concrete.
Pour a concrete base if necessary.
If just want to change your pool completely you have a couple of other options.
The vinyl liner conversion process.
Remove the existing liner and haul it away.
Last but not least you can just change out the liner to give you another 10 to 15 years.
If you could choose any interior surface and cost was not an issue then a properly installed all tile interior surface is the best pool coating that money can buy.
A concrete pool is so much more substantial and so much higher quality than a vinyl liner pool that it seldom makes sense financially for the value of the property to convert a concrete pool to a vinyl pool.
If you are converting a vinyl pool to a concrete pool for the purposes of developing a high end real estate property then paint is certainly not the finish you want in your pool.
With this option you can shallow or deepen the pool.