SQL current timestamp
I changed a few things so that it ended up like this: 

Create TRIGGER [sonfor_ags].[trg_date] ON [sonfor_ags].[MitigationMeasure] 
AFTER UPDATE 
AS BEGIN 
SET NOCOUNT ON; 

    UPDATE t SET DateRemove = CURRENT_TIMESTAMP 
    FROM [sonfor_ags].[MitigationMeasure] AS t 
    INNER JOIN inserted AS i ON t.OBJECTID = i.OBJECTID 
       AND i.Removed = 1; END GO 


and now it works perfectly. Thank you very much