GTS Export document cancellation

Dear Gentleman,

I have few export declartion for 2020, Please help to delete/cancel the export declartion. Because this has been dispatched twice. however this export cannot be processed. It's not allowing me to change mode and giving message that "The document cannot be processed currently due to its status Message No. /SAPSLL/CORE_LEG036". Message type showing M2120 in process.

Thanks

RP