How to improve Python's code speed - Panda Dataframe

Question

I'm new to python and panda, i have a huge dataframe of 2 000 000 rows and 2 columns (small example below)

RECEIVER	TRANSMITTER
UEXRT4E	458ERT56
URTU5FE	458ERT57

And an other one with 304 Receivers.

RECEIVER	Number Received
UEXRT4E	25002
URTU5FE	15004
UFTX5FE	10500

I want to delete every transmitters received by each receivers in the huge dataframe.

To do so I have 2 while running. One to get all transmitters receive by receiver n°1 then 2 etc...

Then an other one to delete all the rows where i see the transmitters.

Variable "u" starts at 0.

 while(u<VCbrutD): 
    uE = CbrutD['TRANSMITTER'].iloc[u] #get the transmitter
    Cbrut.drop(Cbrut[Cbrut['TRANSMITTER'] == uE].index, inplace = True) #delete every input of it 
    u = u + 1
    print(u)

VcbrutD is the max lenght of the previous request where i get all the transmiters for receiver n°1 in my 304 receivers's list.

Cbrut is my huge dataframe with 2 000 000 rows.

First loop isn't taking too much time for getting all the transmitter for one receiver, but unfortunately the second while is taking years to compute.

Moreover i do not want to delete everything at the same time as it is important to start from the receiver with the highest number received then the second one etc..

Any idea how to improve this loop ?

Thanks everyone !