There is nothing wrong in having soft drinks such as Coca Cola as long as they do not contain alcohol.
elaborating on this issue, we would like to cite a Fatwa issued by the Fiqh Council of North America, which goes as follows:

“It is well known that some soft drinks, such as Coca-Cola, Pepsi-Cola, contain among their ingredients a tiny amount of alcohol, which is used to dissolve some constituents of the drinks such as color, flavor, etc.

Coca-Cola and Pepsi-Cola, for example, contain different types of flavors, considered to be part of the trade secrets; these flavors dissolve in alcohol, which is no more than two to three parts in one thousand (0.03-0.02 %) in these drinks.

Such soft drinks are considered to be permissible or halal from the Islamic point of view, according to the rules of eating and drinking in the Islamic legal law.

To anchor this basic concept, we would like to say that if a small amount of a prohibited substance X is mixed with a dominant permissible substance Y till substance X loses all its attributes such as taste, color, and smell, substance X loses the qualifications of being impure and prohibited by having being dissolved in substance Y.

This conclusion is supported by a ruling by Imam Ibn Taymmiah in his book Al-Fatawa (21/502), and by the recommendations of the Ninth Medical Fiqh Seminar of the Islamic Medical Science Organization, which met in Ad-Dar Al-Bayda’ in Morocco in June 1997.

Moreover, The Islamic Food and Nutrition Council of America adds:

In the food industry, alcohol is the second common solvent after water. Some of the flavors like vanilla cannot be made without alcohol. One cannot imagine foods and drinks like ice cream, cakes and cookies, soft drinks, etc. without the use of alcohol, to the extent that this has become an unavoidable impurity in the food systems. Muslim countries, which import food products, accept foods containing small quantities of alcohol.
We have established two levels of control points for alcohol in foods and ingredients:

Less than 0.1 per cent in the food items.
Less than 0.5 per cent in food ingredients.

At the above levels, one can not detect the presence of alcohol by taste, smell or sight.
These guidelines are for the food industry to make halal certified products. However, where should one draw the line is up to the individual Muslim consumer, based on “the available knowledge and his or her own commitment.