How to remove this unnecessary high waveform that prevents me from amplifying to the highest possible (but still fine)db

What’s the work?

You also have the Left sound louder than the Right. Did you want that?

You can use the two AudioBook tools, RMS Normalize followed by Limiter.

RMS Normalize has to be installed separate.

If that’s an audiobook reading, you can Split Stereo to Mono (Using the tools under the drop-down on the left), delete the Right track and follow the whole audiobook process.