In order to unlock tokens one must have a vesting seed and go to https://vesting.bonfida.org/#/unlock
For the sake of the example let's use the following vesting seed
Enter the seed in the search bar and click Search
Once the UI has finished loading the contract an Unlock button will appear as well as the unlocking schedule graph and the current receiver of the locked tokens.
Unlocking tokens is a permissionless instruction. It means that anyone can send this transaction to the blockchain, however, the tokens can only be sent to the receiver of the vesting contract. For example, if Alice is the receiver of a vesting contract and that Bob clicks unlock and sign the transaction with his wallet, the tokens that unlock will be sent to Alice because she is the receiver of the vesting contract.