There is a small building located on the KTEX runway in my FS9. This may have been added froman add-on scenery or from the default. How can I remove this object from the runway?

Well you should probably try to find out whether an addon is reponsible. If you have addons for that airport you may want to turn them off in the scenery configuration and see it that works. It also depends on what type of object it is. The simplest way to remove it would be to create a small exclusion rectangle at that place. However it would be important that the bgl file containing it is at a higher scenery priority than any addon that is causing it, other wise the object won't be excluded