Metadata: Delete a value from IPC-Scene

C1 don't have any metadata for Person Shown in a picture, so I use IPTC Scene because enable several values.
For example "Person1,Person2,Person3" is recorded as
Person1
Person2
Person3

But after using 3 persons for 100 pictures, I want to delete Person2 for a set of 30 pictures and Person3 for other set of 25 pictures.

There is no way to erase a value in a token of metadata that enable multiple values.
The only way I found is to delete on every picture , the copy an paste metadata never delete the delete values.

I'm Media Pro user from the beginning when called iView, then iView Pro, then Expression Media, then Media Pro, then.... NOTHING
Phase One have all the answers in Media Pro for how to do a Library (Catalog management). The best library software never maded....
What we have now on C1 is a library project with few pretensions and very very improvised

For example: changing a metadata label from one value to another in 25.000 images has cost 7 hours.
The same process in Media Pro, cost me a few minutes.
The metadata in catalogs is for changing values, add values, delete values.

Other example:
If I have selected 100 images and add, delete or change Keywords, all the 100 images are changed at the same time.
If I change County, City, Coment, Title, etc only one image is changed an then copy , select tokens to copy and paste?
That is a nonsense!!!