Is it okay to want to destroy my old job?
What makes you want to destroy your old job?
I have a new job now and it's going to be a better one.
It's good to move forward and put the past behind you, but it shouldn't come at the expense of others. Don't burn bridges and try to make things easy for the people replacing you on your job.
Moving forward is better than standing still. I'll do whatever it takes to make sure my old job is set for status quo. There is no need for anyone to replace me.
Stop thinking about your old job and focus on your new one. Your new employer might find out how you are planning to meddle with things at your old job and fire you. Show some maturity and be a professional.