Relationship.SEQN in REST API

To our knowledge, relationship records are stored in the Relationship table and each row as a unique SEQN value.

Is it possible to query relationship records and retrieve this SEQN information?
The case use would be then to be able to delete a Relationship record after finding it via its SEQN value.

In other words, given a Relationship.SEQN a user would want to be able to edit or delete the relationship record from there.