There are some buttons that come with the Trix editor that aren’t going to have a use case in all applications. You can remove them with CSS.
It is a 2 step process, first, find the class of the button you want to remove. Right click on the button and inspect it, it will have a class like trix-button--icon-name-of-button
Then in CSS you can hide it from view with a display:none.
For example in our Pin Trading website we have no need for the following, so we remove them!
.trix-button--icon-increase-nesting-level,
.trix-button--icon-decrease-nesting-level,
.trix-button--icon-strike,
.trix-button--icon-code { display:none; }