The phrase "close doors" can have a variety of synonyms depending on the context and the specific connotation you're looking for. Some common alternatives include "shut out," "exclude," "bar access," "seal off," "restrict entry," "block entry," "prohibit access," and "limit admission." Depending on the situation, you might also use more specific terms like "terminate a contract," "cut off communication," or "sever ties." Choosing the right synonym can help you more accurately convey your intended meaning, as well as create a more nuanced tone depending on whether you want to emphasize control, protection, or disconnection.