how can I remove help menu link on 5.2 ?
This question does not meet the minimal requirements as outlined here. One line questions that don't show anyone what you've done so far to help yourself are less likely to get help from others. For example: What have you tried thus far and where are you stuck?
If what you want is to remove the link in the Share's main menu, then this tutorial has all the information you need: Removing a menu item (Aikau) | Alfresco Documentation
The widget id you have to use is HEADER_USER_MENU_HELP
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