There are a number of series of Indian satellites that have been decommissioned. Some of the most notable series include:

• INSAT: The INSAT series is a series of geostationary satellites that are used for telecommunications, broadcasting, meteorology, and search and rescue. The first INSAT satellite was launched in 1983, and the series has since grown to include over 30 satellites.
• IRS: The IRS series is a series of polar-orbiting satellites that are used for remote sensing. The first IRS satellite was launched in 1988, and the series has since grown to include over 10 satellites.
• GSAT: The GSAT series is a series of geostationary satellites that are used for a variety of purposes, including telecommunications, broadcasting, and navigation. The first GSAT satellite was launched in 2001, and the series has since grown to include over 20 satellites.

These are just a few of the many series of Indian satellites that have been decommissioned. When a satellite is decommissioned, it is usually moved to a "graveyard orbit" where it will no longer pose a threat to other satellites or spacecraft.

Here are some of the reasons why Indian satellites are decommissioned:

• End of life: Satellites have a limited lifespan, and they are eventually decommissioned when they reach the end of their useful life.
• Technical problems: Sometimes, satellites are decommissioned due to technical problems that make them unsafe or unreliable.
• Financial reasons: In some cases, satellites are decommissioned for financial reasons. This may be because the satellite is no longer needed, or because the cost of maintaining it is too high.

The decommissioning of Indian satellites is a regular occurrence, and it is an important part of the management of the Indian space program. By decommissioning satellites that are no longer needed, ISRO can ensure that the space environment is safe and that resources are used efficiently.