Bug when disabling syntax highlighting.
I like to use the plugin with syntax highlighting disabled, as it makes moving faster, but when I disable the syntax, these "Tags" appear on the side and I can't delete.
File Type MarkDown

Hey @GabrielSantos198, thanks for using presenting.vim!
This is a feature, not a bug :D We use a custom syntax HL to improve how e.g. table or headers are rendered, but, and this is the downside, we have to mark these lines: the <<tr>>, <<ht>>, <h1> you see.
Right now I can't think of a quick way of fixing this, except maybe using an older version which does not have this feature enabled. 9fb8ccc626cda329c08a35c1df8deff67768a537 should do the trick.
I'm not planning to changing this right now, but I'm open for suggestions.
I should also mention that there are other alternatives to presenting.vim like https://github.com/Chaitanyabsprip/present.nvim
@sotte Thanks for the answer
I got the same issue even when enabling it "syntax on"