In order to make a drink shrink, you need to first remove all of the liquid from the container. Once the liquid is gone, you can then proceed to shrink the container itself using a heat source.
The most common way to remove liquid from a container is to simply pour it out. However, if you're trying to shrink a glass or other fragile container, this may not be the best option. Instead, you can use a syringe or pipette to remove the liquid without damaging the container.
Once the liquid is removed, you can then shrink the container itself using a heat source. The most common heat source is a blow dryer, but you can also use a heat gun or even a stovetop burner. Simply hold the heat source close to the container and watch as it shrinks down to the desired size.
If you're trying to shrink a plastic container, you may need to use a higher heat setting than you would for a glass container. This is because plastic is more resistant to heat and will take longer to shrink.
With a little patience and the right heat source, you can easily shrink any type of container down to the desired size. Just be careful not to overheat the container, as this can cause it to warp or even melt.