Illia

You can chop the P-stem down in height, yes. Usually a banana needs to be so tall to fruit, and have enough leaves just before flowering to fruit enough and of good enough quality, but you can indeed chop the plant back, especially during dormant times like winter. If you're looking to keep a banana below its expected flowering height, that can be done, but it won't give the best results in the end. If you just want to chop it back for storing or moving ease, it won't hurt it at all. Especially if chopped at a younger age.