You are accessing memory after it has been deleted. That invokes undefined behaviour. There may be a runtime error, or maybe not.
All that it means to delete a block of memory is that you are promising not to use that pointer again. The system is thus free to do what it wants with that memory. It may re-use it. It may do nothing with it initially. You promised not to use the pointer again, but then broke that promise. At that point anything can happen.