How to commute by (electric) bike in excessive heat
You mentioned that you rented an electric bicycle, I am assuming you still need to put in efforts and the motor just provides pedal assist. 
Most pedelecs are limited to providing assist only up to 25 km/h. 
Beyond this speed, the motor is cutoff and the rider has to put full effort to maintain the speed. 
If this is true for your case, you will get the best outcome by maintaing speed just below 25 km/h. 

Also watch your cadence, choose a gear that is not too hard or too easy so your body uses cardiovascular and leg muscles optimally. 

You also mentioned you leave office at noon, so it looks like you are only concerned with the ride back home. 
If sweating is your only concern, keep your self hydrated and go on anyway. 
I would still advise you to follow your instincts and slow down or stop if you are feel exhausted. 
Take a shower once you reach home and cool down for a few minutes. 
Ensure you do not shock your body with too much of a temperature difference though. 

The following are generic points which can help further. 
Midday temperatures can reach 40°C in summer, where I live. 
I plan my rides to avoid the hotter parts of the day. 
My work hours are mostly fixed so commute to office is easy. 
See if you can adjust your timings for this season if you are working in shifts. 

I switched to riding in cycling shorts/jersey and change of clothes at office instead of riding in work dress. 
Along with a good pair of sunglasses, a wet handkerchief under my helmet and another around the neck are useful accessories. 
For longer rides, I found that squirting small amounts of water on my face from time to time feels good. 

Another advice i started following is to ride slow for the last 5 mins etc. to allow my body to cool down. 

When I have to go out in the afternoon or if there is any uncertainty in the duration i might have to spend outside, i take the public transport. 
Car/bike pooling is another option that is still quite eco-friendly. 

I keep myself hydrated with plain water, and with sugarcane juice or tender coconut water for longer rides.