Style note: Reducing relative clauses
You can often reduce adjective clauses that begin with a relative pronoun.
There is some gain in compactness in these clause reductions. However, the reductions do make the sentences a little harder to read, especially for nonnative speakers, so you should consider your audience.
As you work to reduce wordiness, you will find you can often reduce phrases and clauses even further, often with some reordering or substitution:
Occasionally, however, a sentence might be misread without that. In such cases, do not omit that.
Sarah didn’t see the tree; she saw that the tree was gone. The word that tells readers to expect a clause, not just tree, as the direct object of saw.