Can i delete or block specific file in html without source code?

Example

https://i.stack.imgur.com/X4T19.png

Hello, I need help for this question. This is about Webviewer managing CCTV.

I was asked by our company's client not to show a specific menu of Webviewer.

The Webviewer is a local server generated by the CCTV firmware, not by an external web server.

If i have the firmware on CCTV, i can modify the menu part of the source code.

However, the firmware was encrypted and could not be unpacked with numerous attempts.

So I want to find a way to block files for loading in HTML rather than modifying them in encryped firmware.

When loading Webviewer from browser, can i block certain words or picture files?

I want to keep the file deleted like the picture above, even if I refresh it .(The uploaded screenshot was temporarily deleted by the Chrome developer tool. Of course, when i refresh, i will see the word again that deleted.)

The ultimate goal is preventing certain words or pictures to the user in the viewer.

I'm not good at web(frontend) so I need your help.

Thank you for reading my question.