Not by yourself. You can only have one membership at a club (or group of clubs) at a time, so your club must end your current membership before you can buy another.
How to switch
Contact your club and ask them to end your current membership.
Once it has ended, buy the new membership in the app. Or ask the club to add it for you.
If you try to buy a second membership, you'll see You are already a member.
Good to know
You can have memberships at different clubs at the same time.
Ask the club how switching affects any contract period or payment you've already made.