Quite often I come across a requirement when I have a field on the new/edit item form that I want to hide, usually this has already been populated by some development. In this example we have a link field (which in this case links to another sharepoint item) which we want to hide.
1. Open the list, click 'Settings' the 'List settings'
2. 'Advanced settings'
3. Set 'allow management of content types' to 'Yes', click 'OK'
4. Click 'Item' under the 'Content types' header (may not be called item based on the type of list e.g. might be called 'Task')
5. Choose the relevant field (column) that you want to hide
6. Click 'Hidden (will not appear in forms)' then 'OK'
jennye