Reduce complexity by first understanding why each application and interface exists, who depends on it and what business capability it supports. Then look for duplicated capability, unnecessary hand-offs, unclear ownership, point-to-point dependencies and data copied without purpose. The aim is not the fewest systems; it is a landscape whose interactions are understandable, governable and proportionate.
Map relationships, not just inventory
An application list misses the behaviour created by integrations, manual workarounds, shared data and organisational ownership.
Simplify with a sequence
Retire, consolidate, modernise or re-platform in an order that respects dependencies. Removing the wrong component too early can move complexity elsewhere.
Measure the whole
Track support burden, change lead time, data reconciliation, failure modes and ownership — not only application count.
How soapplied approaches the question
I would not start by assuming the stated problem is the whole problem. The first step is to understand the people, purpose, constraints and interactions around it, then test what intervention would improve the system rather than merely optimise one component.