A clipboard is a basic part of the operating system - if you uninstall it, a lot of things will break.
If I understand correctly, your problem isn’t that you can copy your password and have it in the clipboard - every operating system does that. Your problem is that if you click on the “clipboard icon” in the notification area (system tray), then the clipboard widget pops up and your password is shown.
The solution for that is simple - don’t show the clipboard icon in the system tray:
- click the right pointing arrow at the end of the system tray:
- In the widget that pops up, click the “settings icon” (that is called “Configure System Tray”).
- In the System Tray Settings dialog that opens, click “Entries”, scroll down to “Clipboard” and in the pull down choose “Disabled”
You can also choose “Always Hidden” which will move the icon from the visible system tray part to the overflow widget - the one you get when you press the up arrow, with the “Status and Notifications” heading: this will still let you access the clipboard manager menu if you want to, but it will be harder to accidentally click it or hover it.