Show warning and link to more information when changing resource license

As long as you are the only contributor: You can do it, without further problem; otherwise it is difficult.

If others contributed to your project, you have to respect their rights. So you can only assume the rights given to you by the open source license. Your options are:

• contact all contributors and ask for their permission
• switch to a compatible license (this means, if your original license is permissive, it might have a lot compatible options, if it is copyleft, the compatible options may be limited)
• remove contributions of others before switching

As a note: your old version of the software released under the old license can still be used under the terms of the old license. If that license is pretty permissive that may include the relicensing under some other licenses.

More info: https://opensource.guide/legal/#what-if-i-want-to-change-the-license-of-my-project