Flux Cancellation in a Decaying Active Region Flux cancellation is observed in many regions on the Sun as internetwork, network and active regions fields. It clearly plays a crucial role in the constant flux processing observed in the solar surface. During the decay of an active region, we have observed the in-situ dissapearance of 70 % of its flux (from SOHO/MDI). Active region flux decay is a global, large-scale, process crucial to the solar cycle. But the flux cancellations, where the flux actually disappears, do take place in very small scale regions. There opposite polarities meet and vanish. The process needs of observations with sufficient sensitivity and angular resolution. In the example presented here, we show how up to 4 of these cancellations are associated with outward moving material in the Corona (as observed by TRACE), including a major active region filament eruption. Solar Orbiter, profiting from the advantage observing position and near-corotation can follow these subtle, but crucial, processes with the necessary set of instruments: Magnetographs, Coronal imagers and spectrographs. For those events occurring in the spacecraft solar vertical, one should not exclude the detection of the phenomena in the in-situ instruments.