Always remembering that I am not a lawyer, much less an expert in licensing.
Essentially it depends on the license. If she forces you to keep there, it would be a violation yes. Precisely because of this the good tools of minification allow to make exceptions to these comments.
If you put it somewhere on your site, you can probably take these files without infringing the license. Again, you need to see the license's specificity, but it's a solution that I think applies almost universally. Since it is not something hidden, that is unrelated to the use of the files, do not have some trick, I think it is even a way to make more obvious its use.
Some people may interpret that just being together on the server does not have to be delivered to the browser. I would not go this route if you want to be certain that you are not disregarding the license requirement. But if you want to insist on this, I suggest you seek a specialist lawyer.
There is no consensus on this but I see in my humble remark that most feel they need to keep the license in the minified file. If you do not, the risk is yours.
Do not like this? Switch library or do not use one.
Recommended tools to preserve the license (read the documentation to see how to get the desired result):
