Supondo que realmente haja um número na string, você pode usar
patindex()
:select left(s, patindex('%[^0-9]%', s) - 1)
from (select substring(col, patindex('%[0-9]%', col), len(col)) as s
from t
) t;
patindex()
:select left(s, patindex('%[^0-9]%', s) - 1)
from (select substring(col, patindex('%[0-9]%', col), len(col)) as s
from t
) t;