If two charges attract each other; then

The phrase 'canceling out' can mean several things. One very reasonable interpretation is that if we define a system of two unlike charges of equal magnitudes, then no matter what their separation distance, the system's net charge$=0$.

So you can interpret the canceling out as summation of individual charges in any defined system, or net charge equaling to zero.

In our world, protons carry a positive charge and a negative charge is carried by electrons. In a neutral atom, we have an equal number of protons and electrons, and so if we define the atom as a system, the system has zero net charges. In other words, equal protons and electrons nullify each other's properties.

Now we do observe phenomena known as radioactive decay (in many different forms). In K-capture decay, the innermost electron is captured into the nucleus and combined with a proton to form a neutron. But this is a radioactive process and is observed in the radioactive nuclei only.

One must be negatively charged while the other is positively charged

One must be charged while the other is charge deficient​

They must have the same charge

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