You can significantly reduce legal risks by letting someone go without a clear reason. If you say "they don't fit in" some jurisdictions could give the employee room to challenge that decision (they might argue that you are homophobic or that they spurned your advances or some other hard to prove right or wrong allegation). I suggest if you are going to give someone the push, be nice, just tell them its not working out, the business has had to reconsider the situation and you have to let them go. You got nothing to gain by making it ugly, and you could potentially save yourself a head ache with some diplomatic speak.
An extra point worth remembering... "To fire" someone has different understanding geographically speaking. In North America, and in Germany, when you fire someone, you are dismissing them "with cause" (they were doing something illegal or some thing that could negatively impact or endanger the business). You "let someone go" or they are made "redundant" when you dismiss them "not for cause". Redundancy usually is beacuse the business is going thru some belt tightening though it can also be that the company discontinued a product/service and no longer needs employees that previously assisted in that area.