By default, installing the Deep Security Agent (DSA) allows you to automatically install the Notifier as well. When you have Notifier installed, its icon will show to all users.
To hide the Notifier icon, follow this article to install the Deep Security Agent without installing the Notifier on the remote server.
To install the Deep Security Agent alone, run the following command:
msiexec /i Agent-Core-Windows-9.5.2-2038.x86_64.msi /qb ADDLOCAL=MainApplication
After installing the Deep Security Agent only, be reminded that the Notifier will not also be installed in case of upgrading the agent.