I have a list with two content-types. I only want the user to be able to edit or delete listitems created from only one of the content types in SharePoint 2013.
On a quick side note… Using unique permissions on each item can lead to problems with performance as each individual item has to have it’s ACL tested as opposed to permissions at a list level.
Keep this in mind… You need to have a strategy for handling archive on lists like this if you have any serious numbers of items. The numbers probably reached the problem stage with around 8,000 items in a list. This was a time tracking solution and the requirement was that regular users could not see each other’s time sheets.