Closing as not a bug. Browsers use garbage-collected memory, so they do not immediately release resources, only when they collect garbage. So you should not expect destroying objects to immediately release anything. If you have a lot of spare memory, e.g. 4 GB RAM with 2 GB free, and the browser is only using 100mb, it may quite reasonably decide there's no point wasting CPU time running garbage collection. If it does start to run out of memory it will then collect garbage to free up memory, preventing any crashes related to running out of memory due to uncollected garbage.
You can verify this is the case: create 100mb worth of objects, destroy them, open Chrome's dev tools, go to the Timeline tab, and click "collect garbage". The memory use instantly drops down to ~30mb.
If you experience any crashes it is very unlikely to be caused by this, so you need to find what the real cause is and report a bug based on that.