list manipulation – Remove a part from all sublists

You seem to have a problem that Excel puts some errors containing string expressions. If they appear in random places but you know how they look you can delete them based on their pattern. After you import:

data=ToExpression[Import["https://pastebin.com/raw/rSVRyTge"]];

you can remove them whether by exact pattern

DeleteCases[data,{"",-6 ""},Infinity]

or some generalization

DeleteCases[data,{___,_String,___},Infinity]