How to filter whether a cell is contained in other cells？

Hi There, 

I am sorting out more than one thousand phrase information. Since the information is obtained in batches, I have to filter them to ensure that they are unique. They are not repeated, but some phrases are contained in other phrases. Let me give you an example, 

NO. 1  is  safety signs

NO. 2  is  emergency safety signs 

NO. 3  is  emergency signs

You can see the No.2 is included No.1 and No.3, so we need to find them (no1 and no 3 ) out and delete them.

So what kind of function should I choose for filtering, please? This is really important to me, I look forward to your early reply. 

Tks in advance. 

Derek