If you want to cashout, you can not cashout the whole fund you used for the betting, but this depends from betting site to betting site as out of the four gambling sites I have used before, only one allows people to cashout the whole amount if the match has never started, if you can cash out all your money, then do than doubting.
I do not know much about Benin but Madagascar is not bad a country at all, also Uganda playing with Kenya, if you pick Uganda to win, you really need to cashout your fund because this is unlikely to happen. But just still know that game is game, anything can happen, but the chance to this is slim.