My family and I currently are out of Thailand in the US and we currently have an extention of stay in Thailand until Feb 28, 2019. I am working and have a non-B and my husband and children have non-O dependent visas. When we left Thailand, we got a single re-entry permit and my employer in Thailand currently has my work permit. We are currently going to apply for a non-O visa for all of us through a different organization and am wondering if that is possible to do while in the US (our home country) without having to go back into Thailand to cancel it? If so, what are the necessary steps to do this? Thanks in advance.

Your extension of stays will not affect applying for new visas while in the states.

On entry to Thailand you might have a problem using the visas if the immigration officer insists upon using your valid re-entry permits.