I've already tried adding or editing dashboard.css for my custom app and nothing worked.
I've edited splunk/share/splunk/search_mrsparkle/exposed/js/build/dashboardspage.js and I commented the btn btn-primary add-dashboard code:
A small button without text appears, or I can also hide it by adding
Is it OK, or there is another better and proper way?
You could create an additional role through access control for that particular user and now allow them access to Create New Dashboard.
I downvoted this post because that feature is not available in v6.2.3, unable to disable create new dashboard link in the role options.
Next time, just comment this fact instead of downvoting people who are just trying to help out. Not a great motivating factor. Only downvote suggestions that could be potentially harmful for your environment. For some reading on how Splunk community culture and voting etiquette works in this forum, check out this previous Answers post: