Hello AJ
This can be achieved with Roles & Authorizations for particular users, you need to take help from your basis team to give the USER only Parking Authorization , not the Posting Authorization, so that users can remove that particular Authirization Object from his Role. You need to create authorizations with activity 77 (park) and without activity 01 (add/create).
You may refer below threads where same requirement is already discussed
authorization object for park document  de... | SCN
Authorization object for Park/post | SCN
Users only be able to 'Park' the document and w... | SCN
Authorisation only to park and not to post | SCN
Regards
Aniket