When to Remove Backlinks?

Long time computer user here - finally getting serious about his website. For a long time flooring operation - everything has to be whitehat. Don’t need Google penalties.

Finally getting to the backlinks - and low and behold - a crapload of backlinks with both a CF and TF of zero... Which by my limited understanding tells me that not only are they worthless, they are also hurting my site’s rank.

So a few questions for the gurus out there...

Am I correct that they are worthless?

At what level of TF should I be removing them?

Thanks,
Michael