Clear iCloud/keychain passwords

If you are using safari as web browser on Mac " A " and want to remove websites passwords , open safari preferences > click on password and enter admin password , select the website and click on edit and delete the password , ( multiple Apple ID can't be selected and deleted )

See the article Change Passwords preferences on Mac - Apple Support

Note : you don't need to delete keychain as mentioned in the thread it will corrupt normal working keychain , you are using second Mac " B " , export and import keychain items doesn't not push passwords as per the article Import and export keychain items using Keychain Access on Mac - Apple Support

Note: You can’t export passwords from Keychain Access.

The two Mac must be using same browser as safari installed in it , it will not work if Mac " A " has safari browser and in another Mac " B " Chrome is installed .

Read Make Safari your default web browser on Mac - Apple Palaikymas (LT)

Hello Aaron Howse1! Thank you for participating in the Apple Support Communities.

We understand that you want to erase a keychain and you want a to import passwords from Chrome to a new keychain. We'd like to look into this with you to see how we can help. 

The following resources from Apple may help with this: 

Delete a keychain in Keychain Access on Mac

Import and export keychain items using Keychain Access on Mac

Make it a great day!