The honest answer is different depending on who you invited, so here are both.
A professional caregiver: yes
Go to Caregiver Access and find the seat marked Invitation Sent. The small red icon cancels the invitation and returns the seat to open, so you can assign it to somebody else.
A family member: not from the app today
There is no cancel button for a family invitation at the moment. If you sent one by mistake, two things are true and both are mild:
It expires on its own after 14 days, and then it cannot be used.
Until then it holds a spot in your Circle, which can mean you are told there is no room when you go to invite somebody else.
If that spot is in your way, message us with the chat bubble and we can clear the invitation for you. It takes a moment.
We would rather tell you plainly that a button is missing than describe one that is not there.
If they have already joined
That is a different thing: see How do I remove someone from my Circle? Removing somebody takes away their seat, never their account.