Is there any way I can disable others from remixing my project? I don't want my ideas taken.

Unfortunately, no. Once you share something on Scratch, it's free to be remixed, and that's never gonna change.

Ok. I was just wondering because it said someone remixed one of my projects, but it was just an exact copy of mine!

Spindaboy wrote:

Ok. I was just wondering because it said someone remixed one of my projects, but it was just an exact copy of mine!

Then report it.

Based on the Creative Commons License, there are some rights reserved. If you share your project, you agree to the terms that it be remixed as long as the remixer gives credit. The Scratch Team encourages remixing, because they have seen how remixing leads to creative projects.

As the Scratch Team said in a Admin Message/ Alert:
Hi - - - , we took a look at the project you flagged as a copy but found some script changes made, which would qualify the project as a remix and not as a copy. We encourage remixing in the Scratch community, since we have seen how remixing can lead to creative, interesting projects. The website includes a “Based on…” link to give credit to the original author – and we hope that remixers will also give credit in their Project Notes. Overall, we want the Scratch community to be full of creative activity and exciting projects, and remixing helps with that.

The bold and blue text is the Scratch Team's point in the message- remixing is allowed and can lead to creative projects.
If a remix of your project is a exact copy, and you are sure about it, just report the project.