Upvote:2
There are two bus lines for Teide, 342 line and 348 but none of them are good for you. However, Titsa Buses are oriented to transportation, not tourism, so, Maybe the bus won't wait for you when you leave it. Some people use those lines for hiking through Las CaΓ±adas or even to reach the peak. (Maybe this is what you want).
Other options are a taxi, which I think they are too expensive, and a touristic bus but I think they have a schedule, so maybe this one is not an option.
However, as additional information, the road to the Teide only reaches about 2400m but Teide is 3718m tall, so if you want to reach the peak you have to do hiking (about 4-5 hours, and pretty tought. Also you might need to get a permission) or you have to book a trip on cable car which costs about 23β¬ (It is worth it)