Omitting the relative pronoun
The relative pronoun THAT/WHO/WHICH can be omitted when it is the object of the clause. When the relative pronoun is the subject of the clause, it cannot be omitted.
You can usually tell when a relative pronoun is the object of the clause because it is followed by another subject + verb.
The woman who spoke at the meeting was very knowledgeable. >WHO is subject of the clause
The woman (that) he loved was moving to New York. > THAT is object of the clause
I saw the shoes (which) you bought online last week for a better price at a shop in Oss.