Is profit from tax-exempt companies permissible or forbidden?

If your pharmacy rental is under legitimate conditions, then you must fulfill them, as the Prophet, peace and blessings be upon him, said: "Muslims are bound by their conditions." So, if you fulfill the conditions and the rental was with the approval of the authorized party, then there is no harm in what you have earned. This is assuming that the mentioned taxes are permissible; otherwise, there is no harm in evading them if they are unlawful.