I've requested to withdraw my Express Entry application for permanent residence on July 12th however heard nothing from the IRCC since. Does it mean they do not want to allow me to withdraw it, or that they suspect me of misrepresentation and want to make sure I get a 5 year ban (life long ban essentially) ?
It depends on the situation.
If you received a PFL, then it is generally too late to withdraw and IRCC will make a decision in your application based on your response.
If you received an ADR and did not respond to that, I suppose it's possible IRCC will assess your application to determine if they will let you withdraw. I'm not entirely sure about that.
If neither of the above apply, then you should be able to withdraw your application. Generally it can take a few months for IRCC to confirm the withdrawal to the best of my knowledge.