What icon? If you want to remove the module manager, go to client/modules/client_modulemanager/modulemanager.lua and replace:
Code:
moduleManagerButton = modules.client_topmenu.addLeftButton('moduleManagerButton',
tr('Module Manager'), '/images/topbuttons/modulemanager', toggle)
for:
Code:
--moduleManagerButton = modules.client_topmenu.addLeftButton('moduleManagerButton',
--tr('Module Manager'), '/images/topbuttons/modulemanager', toggle)
Then start client, open terminal (ctrl + t) and see if it has any error. If has, check the file and the line giving error and remove/think on a solution.