How do I remove the term ID from the view URL? I have a content view with an exposed filter based on a vocabulary. 

In the URL (for example, mysite/myview?tid=taxonomy+term+(3)), and incidentally in my page title (I use argument.tid to display a title based on the term typed in the exposed filter), there are the name of the term (perfect) but also the term ID.

I only need mysite/myview?tid=taxonomy+term or, better, mysite/taxonomy-term.

How can I achieve this?
Perhaps you can do this using htaccess rules.

You can probably apply the patch from this issue and than according to the reports you will be able to create a path alias from within drupal that accept url parameters (as in your case)

But you can also try views_url_path_arguments which seems to be usable in Drupal 8 judging from the amount of downloads.

Perhaps you can also give this sandbox module Query Parameters To Url a try

Note: I have not tested the above 2 modules