Can a sex offender re- locate to another country while on parole like the uk

No, it's very unlikely. For starters, the UK will not allow a felon from the US to even enter or gain temporary visa status with a conviction on their record. There was an incident that occurred when Martha Steewart tried to enter Great Britain for a business meeting after she was released from prison - she was not allowed to enter. A sex offender will no doubt meet the same barrier.