If the smell is pervasive, try to change your top twice a day and make sure you bring an alcohol and a cotton swab to apply to your underarms before putting on a new top. Some people say this is bad for the armpits so do the next suggestion instead.
However, if it is impossible to change in your workplace inconvenient to carry an extra shirt, remember to always carry a small bottle of alcohol or antiseptic as it is proven to kill 99% of bacteria. Buy yourself one of those spray bottles and when you think the armpits are starting to spew a repulsive odor, spray or squirt alcohol in your shirt's armpits not on the skin.
Check out how you can cure your wet underams naturally and forever.