This is an area of some doubt. But you're probably OK so far as using the image yourself goes.
The major AI platforms' standard terms of use all say that that you own the images generated by their platforms from your prompts, parameters, etc, subject to compliance with their acceptable use policy. So if you use the platform to create images that are obscene, violations of hate speech or racial vilifiation laws, defamatory, breaches of confidentiality, etc, the platform may try to stop you using or circulating the images. But I'll be charitable and assume that you're not going do to that and will strictly confine yourself to images of pixies, pretty flowers and cats playing with balls of wool, in which case, as far as the AI platform is concerned, you can do what you like with the image you create through their platform.
Where it gets murkier is if you attempt to enforce your rights of ownership against third parties. While you own the image as far as the platform owner is concerned, all that means is that the platform owner won't dispute your right to use the image. It's still an open question as to whether there is any copyright at all in the image — while your prompts were one of the inputs involved in the creation of the image there were many others, and it's not clear that your prompts alone are enough to say that you "created" the image in a way that would allow you to assert copyright. So if someone else takes the image and uses it, it's not at all clear that you could do anything about that.