SQL Server: how to disable a Linked Server

DECLARE @Linked_Server_Name sysname = 'SRVZUC02\SQLEXPRESS'

-- check the existent linked servers
SELECT s.is_data_access_enabled, *
FROM SYS.SERVERS s
WHERE s.NAME = @Linked_Server_Name


-- Disable data access
EXEC sp_serveroption 
      @server   = @Linked_Server_Name
	, @optname  = 'data access'
	, @optvalue = 'FALSE'


-- check the existent linked servers
SELECT s.is_data_access_enabled, *
FROM SYS.SERVERS s
WHERE NAME = @Linked_Server_Name

Found here.

About procedure [sp_serveroption] on SQL Docs.