What is the ruling on praying Fajr at work without removing work clothes for Wudu due to cold or work pressures in the security field?

You can perform ablution (Wudu') while wearing work clothes by rolling up your sleeves. If that is not possible, then you must remove whatever prevents the ablution. Work pressure or mere fear of cold is not an excuse to omit some parts of ablution or to resort to Tayammum (definition) (dry ablution).

You must take measures to prevent harm from the cold, such as heating water, performing ablution in an enclosed space, and drying your limbs. If there are no means to prevent harm from the cold and there is fear of it, then Tayammum is permissible. If the fear is due to intense cold, and it is possible to heat the water or use it in a way that prevents harm, then you must do so. If not, then perform Tayammum and pray.

If the legitimate excuse for Tayammum prevents the use of water on all limbs, perform Tayammum for all. If it prevents some but not others, wash what is possible and perform Tayammum for the rest. Tayammum is not permissible merely because the water is cold or the weather is cold if there is no harm or if the harm can be prevented. Rather, it is for cold that causes feared harm and cannot be prevented.