Once you have delted it from yout inbox it is deleted.
You can still RETRIEIVE it by drilling down the INBOX and going to DELETED items & you can retreive it as long as you do not close or shut down AC.
If you do shut down or resart AC , I believe you wil lose the deleted items. Your MESSSAGES & CHARTS will still be there.

Just remember if you do not delte the CHART or the MESSAGE when you open them ,then it will stay in your inbox. If you want to know what was the last time you modified the CHART just look at the TIME you saved it(displayed at the side of the Chart in your inbox) & delete the rest you do not need.
Grenville