Удалите название дня недели и дефис, и все должно работать:
WITH cte
AS
(
SELECT DATENAME(weekday,datefromparts(2020,1,dow.dow)) as WeekDay
FROM (values (1),(2),(3),(4),(5),(6),(7) ) dow(dow)
)
SELECT TRY_CAST(REPLACE(REPLACE(t.dateInTxt,'-',''),cte.WeekDay,'') as datetime),t.dateInTxt
FROM mytable t
JOIN cte
ON t.dateInTxt LIKE '%'+cte.WeekDay +'%'