I'm not totally sure that Beta Tech was in this building (next to Mayo's). Its archived web page gives 7500 Two Notch Road as the Columbia address. However google gives both 7500 Two Notch and 6699 Two Notch as addresses. I suppose they may have had a front office as the main address. I'm pretty sure I can almost read "Beta Tech" on this loopnet listing for the property, and I do seem to recall some sort of school there.
At any rate, assuming I'm not all wet, Beta Tech was a vocational school:
Beta Tech has locations in Charleston, Columbia, Richmond, and Richmond - West campus. Between each of these Beta Tech schools, * we offer adult education degree and diplomas in practical nursing, paralegal law, computer support, computer administration, network tech , medical assisting, business and legal assisting.
Their website www.betatech.edu seems to be inactive now (all the info above is from the Wayback Machine at www.archive.org), so I'm assuming they were a casualty of the recession. The loopnet listing seems to imply that there may be a plan for the whole strip mall (it's kind of an interesting building, especially this vacant part, if a bit hard to get into and out of), but for now it just looks like they are leasing the space to any comers.