Hi Ankita,
submit a support incident to SAP, there can be many reasons the PSA data is not being deleted, usually the reason is that described by Sjoerd, but to correction needs to be analysed, perhaps changing the active and inactive PSA table by debugging can sort the issue out, or perhaps we can run some correction reports.
Whatever you do it is always advisable to avoid making changes via SE14, this can cause inconsistencies in the request admin tables on the application side,
thanks,
Colm