Based on your other post about that keyframe afffecting the chroma key, it looks like something in your project is damaged. Try using File | Save Project As and see if the keyframe can then be deleted.

You may also want to try making a new project with just that clip and see if you're able to place and remove keyframes normally.

In the moment, you should always be able to click on Undo (or type Ctrl+Z) to remove it.

Quote Based on your other post about that keyframe afffecting the chroma key, it looks like something in your project is damaged. Try using File | Save Project As and see if the keyframe can then be deleted.

You may also want to try making a new project with just that clip and see if you're able to place and remove keyframes normally.

In the moment, you should always be able to click on Undo (or type Ctrl+Z) to remove it.

Thanks for your suggestions. We can try to start a new project but we need to keep the chroma key values we currently use. We spent some time to adjust 3 chroma keys in order to hind green background because the green background is not perfect and has shadows. Each chroma key has Color Range and Denoise, which are easy to find (see attached screenshot). But could you please let's know where we can find the keys's "main" values (they reprent where we clicked on green background)?

Thanks & regards.

The easiest way to carry the existing clip into a new project is to simply copy the current clip, then use File | New Workspace to clear the timeline and keep all the existing media in the library.

Now paste the clip onto the timeline and save the project, then see how keyframes behave when you add, change and try to remove them.

If you need to use those same chroma key settings in other projects, you can use File | Insert Project and locate the project with the single clip you just created. That way the clip and all desired settings will be available at any pint in the future.