There are bio-accumulative toxins that really do get stuck in your body. Lead is a good example. Not that the supposed cures being peddled by these people can actually do anything about those.

Also, for the normal kind of toxin, the biggest factor keeping the levels in your body high is continued intake. Reducing that totally makes sense. However, you need to first have a real, based on science, understanding of what those toxins are in the first place and not just randomly blame junk food or 5G radiation, and it needs to be a permanent life style change. A two week "cleanse" does nothing. A juice will not detoxify you. (Depending on the juice, especially how filtered and how sugary it is, it may be healthy for other reasons. Standard orange juice is not, it's way too sugary.)