Is it forbidden to enter Makkah for Hajj from Al-Taneem, or is it obligatory to return to the Miqat after having been denied entry to Makkah subsequent to entering into a state of Ihram, and what are the consequences of removing the Ihram due to this?

If you entered into ihram for 'Umrah as a mutamatti' (one performing 'Umrah then Hajj), and you removed your ihram garments to wear sewn clothes for entering Mecca, you owe a fidyah (expiation) of fasting for three days, or feeding six needy persons, or sacrificing a sheep. After the 'Umrah, you become halal (release from ihram restrictions), and if you intend to perform Hajj, you enter into ihram from Mecca.

However, if you entered into ihram for both Hajj and 'Umrah together (qiran) or for Hajj alone, you owe a fidyah for wearing sewn clothes, and you remain in your initial state of ihram. It is not prescribed for you to return to the miqat. If you commit ihram prohibitions before becoming halal: for those that involve destruction, like cutting hair, there is one fidyah for each category. For those that are for comfort or adornment, like wearing sewn clothes, there is no penalty if you were unaware (of the prohibition).