Issue with External SSD - Any Solution?

I recently used a 500GB Sandisk external SSD to make a Windows 10 installer for a new computer. I now wish to use it again as a 500GB SSD, but it appears that the capacity is now limited to just over 31GB even though I've deleted all of the files on it. Does anyone know how to fix this issue? Thanks in advance and let me know if there are any questions I need to answer.

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Edit: Was a simple fix in disk management, Windows had created a 32GB partition, which I deleted and then made a new one with the full size. Thank you all for the answers :)