1. You are suddenly in charge of fewer things. Decisions that used to be yours are now being made by other people. Responsibilities are being taken off your plate. This implies that your influence is on the decline, and that the company is ready to move on without you.
2. Similarly, you are invited to fewer meetings than usual. This also indicates that your input is no longer valued or required in group discussions – plans are being formed and decisions made without you.
3. Your company is suffering financially and there are talks of cutbacks and projects being cancelled. Companies generally only cut staff as a last resort, but when the bottom line is on the line, reducing staff is one way to cut costs and overhead.
4. Your manager starts avoiding you. If a manager who used to spend time with you suddenly becomes distant, avoids eye contact and stops mentoring, it could be that they know you’re on your way out. In that case, coaching becomes unnecessary, and socializing awkward. It could also indicate that they have impending bad news that they are not prepared (or authorized) to share with the team yet – and so are avoiding all contact. 
Be careful not to let paranoia about someone else’s behaviour become a self-fulfilling prophecy. Stay friendly and upbeat with your boss. Look for chances to small talk. Book a one-on-one meeting for feedback or advice on a recent project. A change in someone’s attitude may actually have nothing to do with you – or the future of the business.
5. You start to receive written warnings about minor infractions. This could be a sign that your employer is planning to let you go and that they want to protect themselves from wrongful dismissal claims. They can do this by building up a paper trail of official warnings about workplace behaviour or performance in advance. 
While no one likes being micromanaged and constantly criticized, you should accept constructive criticism gracefully and use it as an opportunity to learn. But keep your eyes open, if this really is turning your workplace into an unpleasant place to be – start your job hunt. Also be sure to document all of your success and achievements.
6. You’re suddenly asked to document everything you do – or train someone on things that are normally your sole responsibility. This can indicate that the company doesn’t expect you to be around much longer – so they’re making sure that someone knows exactly what you do and how to do it. You could also be being groomed for a more senior position – but you can usually tell which way the wind is blowing. Be alert to the signs. 
If you suspect that your company is actively trying to replace you – you should actively (but quietly) be looking for a new job.
7. A new manager being brought in is always a risky sign too. New leaders are sometimes put in place to make changes – and this can include a change in staff. Managers often want to bring in their own teams that they have worked with before, and people naturally feel more loyalty to workers that they hired rather than inherited.

Reference: Workopolis