Hi Suchit,
According to my understanding, the picking strategies are usually defined to enable to feature of transfer order creation automatically using the defined search strategies while conversion from transfer requirements.
So, if you confirm the open TO's and convert the open TR's into TO's and confirm then and then remove the picking strategies then it should not affect the system otherwise. Make sure to remove all the linkages otherwise the system may throw error while processing the TO.
Regards
Subhasis