How do I delete duplicate cells?

[Guest]

Is there a way to delete cells if they are already listed on a separate
spreadsheet?
For example, I have two list of names (list A & B)

List A List B
dog cat
cat goose
monkey
kangaroo
goose

Since cells containing cat and goose are in list B, is there a function that
will delete those cells from list A?

 

[Guest]

One formulas play to get there ..

Assume List A is in Sheet1 col A, List B is in Sheet2 col A,
data assumed from row2 down

In a new Sheet3,

Put in A2:
=IF(ROW(A1)>COUNT(B:B),"",INDEX(Sheet1!A:A,MATCH(SMALL(B:B,ROW(A1)),B:B,0)))

Put in B2:
=IF(Sheet1!A2="","",IF(ISNUMBER(MATCH(Sheet1!A2,Sheet2!A:A,0)),"",ROW()))
(Leave B1 empty)

Select A2:B2, copy down to say, B100,
to cover the max expected extent of data in Sheet1's col A

Col A will return the required results neatly bunched at the top,
ie items in Sheet1's col A not found in Sheet2's col A.

(Hide away the criteria col B, if desired)