u/2months2long

I recently purchased this lemon tree from Costco. I will be re-potting it into a bigger pot and bringing it outside once it warms up. However, from my research, any growth below the grafting line should be pruned. There is a branch growing below where I suspect the grafting line is, but there appears to be a fruit growing from it as well… should I just cut this branch or leave it and see what happens?

I want to give my tree the best life I can, any advice would be appreciated as well! I have a west facing balcony.