Hi Emo,

why I'm asking is because if you want to keep the square (blue "face") then you can e.g. use the split polygon with the two lower vertices (yellow)... then you should have a whole faced square... and then you can e.g. just delete the rest (purple) e.g. by selecting them as faces...

otherwise it might also be possible to select the "orange" vertice and pointsnap it to the nearest yellow vertice, and then merge it with a value of 0.001, and then delete the "green" vertice...

but I'm just not sure what exactly you want... hope this is not to messy explained...

regards

Strarup