No, you cannot delete it. The launcher is mandatory for both single-player and online modes. If you delete gtavlauncher.exe, the main GTA5.exe will refuse to start, displaying an error that Rockstar Games Launcher is missing.
Workarounds (Use with caution):
The launcher gets stuck trying to connect to the Social Club servers.
If you are experiencing issues right now, follow this path:
Because gtavlauncher.exe interacts with the internet, your antivirus, and your system’s permissions, it is prone to several frustrating errors.