ADTech's advise re. using a splitter with only the needed ports is the best option. If you have cables attached to a splitter already, and you opt to leave them in place, perhaps anticipating using the capacity in the future, you can install the terminator at the end of the cable or disconnect the cable and cap the unused splitter port with the terminator.
If the splitter is outdoors, I'd leave the cable connected to the splitter to keep weather out of the cable. Terminate at the TV end of the cable run.
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