If you want to use Lightroom, select all of the files that create the panorama from the Grid view in the Library module. Use the Photo> Photo Merge> Panorama command from the LIghtroom menu. Lightroom will create one file from your multiple files, and no seam will be visible. There should be about 1/3 of the image overlapping from one file to the next. The software will pick and choose from each of the files that come up against one another to create the smoothest seamless appearance.
If you want to use Photoshop, there is a command that will accomplish the same thing, and will keep each file on it's own layer, with a mask to conceal what is not necessary from each layer. The overlap is still required. In this case the command is File> Automate> Photomerge> which will bring up a dialog box where you can navigate to the folder where the files are. There are a number of choices regarding how you'd like Photoshop to 'blend' or 'merge' the photos. You can try different ones to see what is best for your situation.
Good luck!
