1) Use this query to get the UOW (a GUID) of the offending transaction:

use master

select distinct req_transactionUOW from syslockinfo

Note: Ignore the UOW records that are all zeros. “00000000-0000-0000-0000-000000000000”

2) Use the Kill command, replacing the GUID below with the req_transactionUOW obtained from the query above, to kill the offending transaction:

KILL ‘D5499C66-E398-45CA-BF7E-DC9C194B48CF’

Repeat for each orphaned transaction.