@Moses D.K Sopay - Welcome to Microsoft Q&A and thanks for reaching out to us.
Apologies for the inconvenience caused, but at https://azure.microsoft.com/pricing/offers/ms-azr-0003p, Sierra Leone is not listed as a supported country/region.
So, at this moment, there is no option of selecting this country for pay as you go plan.
Hope this helps. and please feel free to reach out if you have any further questions.
Please don't forget to "Accept as Answer" and click "Yes" if the above response is helpful, so it can be beneficial to the community.