To remove Sublime Text 3 snippets is a bit cumbersome as they are stored directly in the packages. But they can be overwritten by adding a snippet with the same name in the packages folder.
To make life a bit easier there is a package called PackageResourceViewer available in Package Control. Install it and run PackageResourceViewer: Extract Package. Then choose the language which snippets you want to disable. All files are now copied to your Packages folder (a subfolder for each language). You can edit the .sublime-snippet or .sublime-completions files. If you simply like to disable the snippet remove all content of its file and save it. Empty files are considered as if there was no snippet.
I know this is still a bit cumbersome but the only way I know until the developer adds an option to turn snippets off.
In addition it pointed out to be important to mention, that of course it is a good idea to delete all (by PackageResourceViewer) generated files except for the ones you wish to modify. Otherwise you won’t receive updates on any of these files if a package gets updated later as @Tobia pointed out in his comment.