SQL Server: how do I kill a -3 SPID?

Question

There's plenty of information about positive SPIDs and even -1 and -2 but I haven't found any information on Blocked By -3. Would anyone be able to help?

GUID is all 0's, and when I run sp_who2 on MASTER db it shows a SPID of 56 as RUNNABLE on the tempdb but when I try to kill it or run sp_who2 on tempdb it doesn't show up, while the MASTER and tempdb sp_who2 instances are both SPID 54.

Edit: When running SELECT * FROM sys.sysprocesses WHERE spid = 56 this is the output for the SPID that's getting blocked:

spid    56
kpid    10500
blocked -3
waittype    0x0006
waittime    313816
lastwaittype    LCK_M_IS                        
waitresource    TAB: 5:1668253048:0                                                                                                                                                                                                                                             
dbid    5
uid 1
cpu 0
physical_io 0
memusage    4
login_time  02:44.3
last_batch  02:44.5
ecid    0
open_tran   0
status  suspended                     
sid 0x0105000000000005150000003DBE35AE805F26A82A34E78AE903000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
hostname    DESKTOP-JOS7UMG                                                                                                                 
program_name    Microsoft SQL Server Management Studio - Query                                                                                  
hostprocess 11364
cmd SELECT
net_library LPC                                                                                                
context_info    0x0000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000
sql_handle  0x01000500C609543A909F01271002000000000000
stmt_start  124
stmt_end    356
request_id  0

Edit2: When running select req_transactionUOW from master..syslockinfo where req_spid = [SPID Number] and KILL '[UOW Number]', the output req_transationUOW comes up all 0's and I get the following error when killing it:

The distributed transaction with UOW {00000000-0000-0000-0000-000000000000} does not exist.

Edit 3: When I run select * from sys.dm_exec_requests the below row is the output. Anything in here I can kill? SPID doesn't unblock the table and I don't want to go killing things all willy-nilly in case it crashes the server.

session_id  59
request_id  0
start_time  10:23.4
status  suspended
command SELECT
sql_handle      0x020000007509B2241E0ED80CA5FE2A1542C26EF873795AB30000000000000000000000000000000000000000
statement_start_offset  0
statement_end_offset    68
plan_handle 0x060005007509B224D06FB16B1002000001000000000000000000000000000000000000000000000000000000
database_id 5
user_id 1
connection_id   E63659D9-A41B-4FAE-89B2-6026AE51B938
blocking_session_id -3
wait_type   LCK_M_IS
wait_time   4246
last_wait_type  LCK_M_IS
wait_resource   OBJECT: 5:1668253048:0 
open_transaction_count  0
open_resultset_count    1
transaction_id  374312
context_info    0x
percent_complete    0
estimated_completion_time   0
cpu_time    0
total_elapsed_time  4247
scheduler_id    3
task_address    0x0000021236EC8108
reads   0
writes  0
logical_reads   2
text_size   2147483647
language    us_english
date_format mdy
date_first  7
quoted_identifier   1
arithabort  1
ansi_null_dflt_on   1
ansi_defaults   0
ansi_warnings   1
ansi_padding    1
ansi_nulls  1
concat_null_yields_null 1
transaction_isolation_level 2
lock_timeout    -1
deadlock_priority   0
row_count   1
prev_error  0
nest_level  0
granted_query_memory    0
executing_managed_code  0
group_id    2
query_hash  0x496ED8C805DE7CAA
query_plan_hash 0x36444CF46922D91E
statement_sql_handle    NULL
statement_context_id    NULL
dop 1
parallel_worker_count   NULL
external_script_request_id  NULL

Answer 1

SPID -3 is a deferred transaction from what I was able to find online. To kill it:

1. Find the UOW Number

   select req_transactionUOW from master..syslockinfo where req_spid = [SPID Number]

2. Copy the UOW number from step one

   KILL '[UOW Number]'

This will kill the negative SPID to resolve the issue.