Q: Is there any simple way to remove Gutenberg editor H1 H5 H6 and change the label for the rest H2 H3 H4? I have been looking for a solution for sometime now. Have not found any one yet...
All we all know every page should have only one H1 tag, however it is not known for most of the non tech editor. I want to restrict the heading option. So there will be no confusion. Better yet, if we can change the label to L, M, S for H2 H3 H4. It will make more sense. one article should not have more than 2 sizes of heading in fact.
Thanks

A: Before WP 5.9 it was possible to get rid of some heading types with CSS like this:
.block-library-heading-level-toolbar .components-toolbar-group {
    button:nth-child(1), button:nth-child(5), button:nth-child(6) {
        display: none;
    }
}

Since WP 5.9 the HTML code has changed. Now you can hide H1, H5 and H6 like this:
[aria-label="Heading 1"], [aria-label="Heading 5"], [aria-label="Heading 6"] {
    display: none;
}

