Can I get back the balance I offered to another Karoot User Account and how?

Of course you can get back the balance you offered to another karoot user account as long as it is still available (not consumed by the user).
To delete the remaining balance from the amount you have offered to a beneficiary, follow the steps below:
1) Go to the "Balance" menu
2) Select the "Beneficiaries" tab
3) Find the beneficiary whose remaining balance you want to return to your account and press the "Delete" action to the right of the beneficiary
4) In the message that will appear asking for confirmation of the beneficiary's deletion, press "Yes".
The available amount of the beneficiary you deleted has now been added to your balance.