The most important aspect of the height you release the bowl at is the consistency with which you do so.
When a wood bounces it will lose some of its momentum as opposed to if it runs smoothly along the ground.
The higher you release, the more variable this is likely to be so it is best to have a release height as low as you can consistently reproduce.
If you cannot release lower due to physical limitations do not see this as a problem though! There are exceptional bowlers who release the bowl relatively high.
Top Tip : If you have lost your line or weight then this can sometimes be to your body position having risen a little by increment. As you look for the same release height this can cause you to move your release point forwards.