You don't unlock these, you root them and it can be done by anyone who can follow the instructions, there are several web pages which give clear instructions, download these, the appropriate free ware and proceed, step by step.
Most important is to back up all your data, numbers, etc in case it goes pear shaped.
Do note that these 'rooted' phones will no longer accept sony updates and will have to be manually updated as per the rooting process.