@Roberto-La12345 
you can't do it in kasa account, but you can connect switch with multiple Smart Things or IFTTT accounts and share switch there, or, simply, ask Alexa to control switch. 
Also it is recommended to use Home Assistant with kasa based installations, so you can do wahtever you want there, but, unfortunately, not in kasa original app.
I remember a post where TP-Link employee mentioned they will not allow more than one home account for security reason, and you know, I can agree with this point of view, but it is all beyond my understanding why there is no local guest subaccount available.