shell and TI work
A little late, but perhaps ever so slightly better than never....
You cannot "delete" a Phase, but you can "get rid of" a Phase by merging it into another Phase. I suppose, in theory, you could do a commercial building with leased spaces and do tenant fitouts as Phase(s) to the original core and shell model, and then continue to use that model for the life of the building, adding a new Phase for every tenant renovation/new tenant fitout. But I would imagine that file would become difficult to work in, particularly if you were to try to maintain all of the Sheets.
I would probably lean toward @Sahay_R's recommendation of a separate fitout model into which the core/shell model is linked. You can still use phasing - the completed core/shell model could be brought in as being the "starting conditions" Phase. (I dislike using Existing and New for Phase names, as those same names are used to describe the relative state of an element in comparison to the Phase assigned to a View.) But if you were to do it all in the same model, I would think you would want to archive the model after the completion of each fitout Phase, and then delete the Sheets (or, most of them - the ones with views of the model for the previous work for sure; you might be able to keep certain detail sheets, particularly if they are all based on drafting views and the details will be the same in the next fitout). The previous fitout's Phase could be merged back into the "starting conditions" Phase, and then a new fitout Phase created for the next fitout work.
Where it gets tricky is if you have multiple fitouts under development at the same time, and you have to keep them separate for documentation purposes, but you cannot predict which one will go ahead first.
